Narrative:

ATIS reported wind 200 degrees at 9 KTS when we left the gate. Prepared for maximum power takeoff due to the tailwind. ATC cleared us into position and hold and then shortly thereafter cleared us for takeoff and stated wind 180 degrees at 15 KTS. We started to look up tailwind component and then determined in our heads that we were at the 10 KT limit and good for the takeoff penalty. This proved to be wrong once we doublechked ourselves at cruise, the tailwind was 12 KTS. The doublechking should have occurred on the ground by asking for time on the runway or exit the runway and verifying the numbers. Our actions are not the way we train or normally execute our duties. But serves as example of importance to verify and not rush when questionable data arises.

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Original NASA ASRS Text

Title: MD80 FLT CREW REALIZES AFTER TKOF THAT THEY DEPARTED WITH A 12 KT TAILWIND WHEN ONLY A 10 KT IS ALLOWED.

Narrative: ATIS RPTED WIND 200 DEGS AT 9 KTS WHEN WE LEFT THE GATE. PREPARED FOR MAX PWR TKOF DUE TO THE TAILWIND. ATC CLRED US INTO POS AND HOLD AND THEN SHORTLY THEREAFTER CLRED US FOR TKOF AND STATED WIND 180 DEGS AT 15 KTS. WE STARTED TO LOOK UP TAILWIND COMPONENT AND THEN DETERMINED IN OUR HEADS THAT WE WERE AT THE 10 KT LIMIT AND GOOD FOR THE TKOF PENALTY. THIS PROVED TO BE WRONG ONCE WE DOUBLECHKED OURSELVES AT CRUISE, THE TAILWIND WAS 12 KTS. THE DOUBLECHKING SHOULD HAVE OCCURRED ON THE GND BY ASKING FOR TIME ON THE RWY OR EXIT THE RWY AND VERIFYING THE NUMBERS. OUR ACTIONS ARE NOT THE WAY WE TRAIN OR NORMALLY EXECUTE OUR DUTIES. BUT SERVES AS EXAMPLE OF IMPORTANCE TO VERIFY AND NOT RUSH WHEN QUESTIONABLE DATA ARISES.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.